Download Our Earth

Our Earth
Not What You Think
 Earth is not a perfect
sphere
 Oblate Spheroid
 Slightly flattened
sphere
 Spinning on the axis
causes the polar
regions to flatten
and the equatorial
regions to bulge
Hydrosphere
• Made up of all the
•
earth’s water
Earth is 71% covered
by water
– 97% saltwater
– 3% fresh water
Atmosphere
• Blanket of gas
• Provides air to
•
breathe
Shields from radiation
– 78% nitrogen
– 21% oxygen
– 1% other
Zones of the Earth
Crust
Mantle
Core
The Geosphere is
The Crust
 Thin, solid, outmost zone
 Only 1% of earth’s mass
 Two kinds
 Oceanic crust
 Continental crust
The Mantle
Makes
up 2/3 of the earth’s mass
Divided into 2 regions
Lithosphere
Lithosphere
•Upper part of
mantle
•Rigid
•Cool and brittle
•15km- 300km
The Mantle
Asthenosphere
•Under enormous heat and pressure
•Solid rock has the ability to flow
(plasticity)
•200 km thick
The
Core
Made mostly of iron
Makes up 1/3 of earth’s mass
Outer Core
 Dense
Inner Core
liquid layer
 2250 km thick
 Dense,
solid
sphere
 1228 km thick
The Layers
were discovered
by studying
seismic waves:
vibrations that
travel through
the earth.
Two Types of Seismic Waves
Primary Waves: P waves
Travel through liquids,
solids, and gases
Travel faster than S waves
Secondary Waves: S waves
Only travel through
solids
The Moho
*boundary between the crust and
the mantle
*seismic waves speed up
-indicates the mantle is more
dense than the crust
Shadow Zones
*Locations on the surface where
neither S waves or P waves are
detected OR only P waves are
detected.
*Occur because of differences in
rigidity
Magnetosphere
• Region of space
affected by the
earth’s magnetic
field
The Source?
Liquid iron in the
outer core
May be another
source
Force of attraction that
exists between all matter in
the universe
Sir Isaac Newton


Law of Gravitation:
force of attraction
between any 2
objects depends on
their masses and the
distance between
them.
Larger the mass and
the closer together,
the greater the force
Weight
Measure of the strength
of the pull of gravity on an
object
Mass
Measured in newtons (N)
Depends on the object’s
mass and its distance
from the earth’s center
The amount of matter in
an object
Does not change with
location
The Earth in Space
Rotating Earth
►Rotation
 Spinning on the
earth’s axis
 1 rotation = 24
hours
 Rotates from
west to east
Revolving Earth
Movement of the earth around the sun
1 revolution= 365.24 days
Perihelion
 Closest point to
the sun
 January 3
Aphelion
 Farthest point
from the sun
 July 4
The Seasons
Caused by changes
in the angle at which
the sun’s rays strike
the earth’s surface
If the North Pole is
tilted away from the
sun, the angle of the
sun’s rays on the
Northern Hemisphere
is lower = winter